Hi LucaradioIt seems to be that Lumion have no support for multi GPU (at least with full capacity yet)...i have a GTX 590 and iÂ´ve experienced the same problems...but runs great with the single GTX 580 anyway... i think itÂ´s not a matter of if, but when... For me, as the seeking for more realistic images (static and moving ones, RT aswell) will keep on growing, with the adition of more, and more effects and post processing to use on the scenes (lighting, etc...), the demand for multi GPU will naturaly occur...weÂ´ll keep wating for the multi GPU support.RegardsFÃ¡bio